1. 3D Force Microscope (3DFM): Laser Tracking and Force Application CISMM: Computer Integrated Systems for Microscopy and Manipulation Collaborators: Dr. William Davis, Dr. Ric Boucher Project Lead: Dr. Richard Superfine Investigators: Jay Fisher, Ben Wilde, Kalpit Desai, Leandra Vicci, Jing Hao http://cs.unc.edu/Research/nano/cismm/3d/index.html 5 December, 2003 A view of the system with six poles in place atop six coils (top coil drive ring is missing). Overview Force Generation Left: Simulated data shows all vectors for which we expect to be able to pull beads using the tetrahedral geometry. Center and Right: Actual data obtained by energizing the magnets with random drive currents. MaterialManufacturerFabrication TechniqueThicknessPermeabilitySaturation 1. Co-Netic AA Perfection Annealed Magnetic Shield Corporation Laser Cut100 microns30,0008,000 Gauss 2. Medium Permeability Foil MuShieldLaser Cut250 microns12,00015,000 Gauss 3. Low Permeabiltiy Foil MuShieldLaser Cut175 microns30019,000-21,000 Gauss 4. Permalloy (10% Fe, 90% Ni). Electorplated Material In houseElectroplated30 microns Left: Maximum forces generated by 4 pole system. For these tests the pole was pushed inside the sample chamber to decrease distance between the pole tip and bead Right: Tetrahedral magnet system used in first generation 3DFM Left: X-tracking signal obtained by x translation of a 1um polystyrene bead through the laser Right: Y-tracking signal obtained by y translation of a 1um polystyrene bead through the laser Left: Z-tracking signal obtained by z translation of a 1um polystyrene bead through the laser Electro Plated Poles Laser Machined Poles Force Calculation Method 1.Laser/Video track moving bead. 2.Plug bead velocity into Stokes law Stokes law F = 6 πaηv, F is the force a = bead radius η = fluid viscosity v = particle velocity The equation holds at low velocities which are free from turbulence (called the Stokes region). General The latest version of the 3DFM, built on a Nikon Eclipse 2000-E microscope, allows users to apply up to 10nN of force while laser tracking beads with 10nm, 1msec resolution. Force application via a hexapole system should provide unlimited directional control of magnetic beads inside samples (compare to tetrahedral data below). Short focal length demands thin pole plates. System designed to meet demands. Six poles are used to generate a hexapole system, with a laser used for particle tracking. Laser Tracking System Optics 1. Tetrahedral Geometry2. Hexapole Geometry The current magnet system. In this image, the system is open, waiting for a sample to be inserted. In this image, the system has been closed and is ready to be energized. Tracking Laser 830nm Excitation <580nm Halogen 650< <750nm? Emission 550< <604nm Tracking Lower Dichroic Tracking Upper Dichroic CCD Tracking Block QPD Fluorescence Block Halogen Filter Sample Tracking Turning Mirror Video Cam Power Meter Tracking Laser Assembly Additional Linear Filter Housing In Nikon Holder on top Roper CCD Cam Fluor Dichroic Hg Arc